How many US Presidents have been elected without winning the popular vote?
Four:
1824: John Quincy Adams wins despite having fewer popular votes and fewer electoral votes than Andrew Jackson. None of the candidates win the majority of electoral college votes, due to two other candidates running, leaving the House of Representatives to choose the winner. All four candidates were of the same political party (Democratic-Republican). Andrew Jackson won the next two elections, making Jackson one of only three presidents to have won the plurality of the popular vote more than twice (the others being FDR and Cleveland).
1876: Democrat Samuel J. Tilden had 51% of the popular vote compared to Republican Rutherford B. Hayes' 47.9%. Twenty disputed electoral votes were controversially awarded to Hayes on the condition that federal troops be withdrawn from the South, effectively ending Reconstruction.
1888: Democrat Grover Cleveland wins the popular vote but loses reelection after narrowly losing his home state of New York to Republican Benjamin Harrison. Harrison lost his reelection bid to Cleveland in 1892, making Cleveland the only president to serve two non-consecutive terms and one of only two to have won the majority of the popular vote more than twice (the other being FDR).
2000: Democrat Al Gore obtains more popular votes than Republican George W. Bush, but Bush wins the election after the Supreme Court rules in Bush v. Gore that Bush had narrowly won the state of Florida, thereby granting him victory by a margin of five electoral college votes.